The present invention relates to ultrasonic transducers, and in particular to ultrasonic transducer probes with additional functionality.
Ultrasound transducers convert between electrical and acoustic energies for imaging a patient or region of interest. Transducer elements are typically piezoelectric materials. A one or two-dimensional array of elements of piezoelectric ceramic or composite materials convert between acoustic and electrical energies. More recently, capacitive membrane ultrasonic transducers have been made. Using CMOS or other similar techniques, a flexible membrane structure is micro-machined on silicon or other semiconductor. By placing an electrode on each side of a gap defining the membrane, the transducer converts between electrical and acoustical energies.
An array of transducer elements are housed within a probe housing. For example, a housing is adapted to be held by a user and placed adjacent to the skin on an external surface of the patient. Other examples include catheter, endoscope, transesophageal and vaginal probe housings.
Other devices have been placed within a probe housing in addition to the transducer elements. For example, a transesophageal probe includes a separate tube with a thermister positioned inside the tube. As another example, U.S. Pat. Nos. 6,511,427 and 6,338,716 disclose position and orientation sensors within a housing. Using magnetic coils, the orientation and movement of a transducer housing is determined. As yet another example, U.S. Pat. Nos. 6,795,374 and 6,461,299 disclose using a membrane of a CMUT transducer to also sense pressure, such as for altering a bias voltage applied to the membrane.